The present invention relates generally to horizontal directional drill machines. It relates particularly to a stakedown assembly for a horizontal directional drill machine.
A horizontal directional drill machine is a common and well-known machine for installing pipes beneath the ground and generally parallel to the surface. These machines are used in many different applications and are available in a wide range of sizes. Typical applications where a horizontal directional drill machine might be used include the installation of fiber optic cables, electrical cables, gas lines, water systems, or sewer systems. Horizontal directional drill machines are commonly rated in terms of pull-back capacity. Some machines for smaller applications have as little as five thousand pounds of pull-back capacity. Other machines are available with a pull-back capacity of as much as one million pounds.
One alternative to a horizontal directional drill machine is the traditional trencher machine. A trencher machine simply digs a trench into the ground, and after (for example) pipe is laid down in the bottom of the trench, the trench is filled and the pipe is buried. The advantage of a horizontal directional drill machine over a trenching machine is that a pipe can be buried in the ground over long distances without digging a trench. Thus, a horizontal directional drill is particularly desirable when a trench would be difficult or too costly to dig. For example, a horizontal directional drill machine finds particularly advantageous application for installing pipes under roadways, where destruction of the road is expensive and inconvenient to travelers, or under a waterway like a river, where trenching would be impossible.
A unique aspect of a horizontal directional drill machine is the special drill head that is attached to the front end of a pipe to be laid. The drill head has an angled shape which allows the operator to change the direction of the pipe after it has entered the ground. Direction changes are achieved by stopping the pipe and drill head rotation and orienting the drill head at a desired angle. Then, by pushing on the drill pipe without rotating it, the drill head and attached pipe will veer in the desired direction. Thus, by affecting directional changes to pipe travel, a pipe might enter the ground at an angle, travel horizontally over a long distance, and exit the ground at another angle. This ability to change the direction of pipe travel also allows the operator to steer the pipe around underground obstacles like boulders.
In addition to pushing forces which must be applied to the pipe as it is inserted, it is often necessary to pull back on the pipe. This may be necessary when a direction change is not completely successful on the first attempt, or when an underground obstacle like a boulder is encountered. The machine then pulls the pipe and drill head back to permit a direction change.
The push and pull forces that a horizontal directional drill machine must apply to the drill pipe frequently exceed the weight of the machine itself. Therefore, a system is required to anchor the machine and resist these forces. The most common system for anchoring the drill machine comprises the use of stakes mounted on the machine body which are screwed into the ground. The stakes have flighting on their tips and are driven into the ground by applying simultaneous rotational and vertical driving forces to each stake. To drive and remove these stakes, a stakedown assembly is conventionally provided on the end of the drill machine where the drill head enters the ground.
Often it is necessary to move a horizontal directional drill before the entire pipe length has been drilled and the job completed, however. This can occur because another project becomes more urgent or when repairs to the machine are needed. Additionally, horizontal directional drill machines are expensive. Therefore, some operators find it necessary to remove the drill machine from the job site each night to protect their investment. However, in order to achieve optimal drilling results, it is desirable to avoid restaking operations. Among other deleterious effects, the removal and later reinstallation of the stakes can weaken the underlying soil, and thus reduce the push-pull forces that can be resisted.
It is therefore desirable to facilitate quick and easy coupling between the horizontal directional drill and the stakedown assembly. Such coupling would allow the operator to easily disconnect the drill from the stakedown assembly. The stakes could then be left installed in the ground while the drill was transported elsewhere. When the drilling operation is later continued, the drill can be reconnected to the stakedown assembly without the need for a restaking operation.
It is an object of the invention to provide a new and improved coupling for quickly and easily connecting and disconnecting a stakedown assembly and a horizontal drill machine.
According to the invention, the coupling includes a first coupling member that is pivotally attached to the drill and a second coupling member that is integrated with the stakedown assembly. The first coupling member is acutely angled on its front end and obtusely angled on its rear end. The second coupling member has substantially matching angles so that the first member fits within the second member in the attached position.
A locking mechanism is provided for binding the two members together in the attached position. This locking mechanism is installed within the first member. In the preferred embodiment, the locking mechanism includes a tapered pin that wedges into matching holes in the first and second members. A cam is used to engage the pin, while a return spring disengages the pin.